SR 519 I NTERMODAL A CCESS P ROJECT P HASE 2: S OUTH ATLANTIC C ORRIDOR Transportation Discipline Report Prepared for Prepared by: THE TRANSPO GROUP Final February 2008 TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS.................................................................................................................... XI GLOSSARY OF TECHNICAL TERMS .................................................................................................................XIII SUMMARY ..................................................................................................................................................... XV 1 What is the Proposed Action and why is it needed? ........................................................................................ xv 2 What is the affected environment?.................................................................................................................. xvi 3 How were the effects of the project on transportation analyzed?....................................................................xvii 4 What transportation effects could occur during construction of the project, and what mitigation is proposed? ......................................................................................................................................................xviii 5 What transportation effects could occur during operation of the project, and what mitigation is proposed? ....................................................................................................................................................... xix 6 What would be the cumulative effects related to transportation? .................................................................... xxi 7 Are any of the identified effects considered substantial? ................................................................................xxii 8 What effects associated with transportation would occur if the Proposed Action is not built?.........................xxii CHAPTER 1 INTRODUCTION...........................................................................................................................1-1 1 Why is transportation considered in the Environmental Assessment?............................................................1-1 2 What is in this report? .....................................................................................................................................1-1 3 What are the key points of this report?............................................................................................................1-2 CHAPTER 2 DESCRIPTION OF ALTERNATIVES.................................................................................................2-1 1 Why is the Phase 2 project needed?...............................................................................................................2-1 2 What is the purpose of the project?.................................................................................................................2-3 3 What are the project alternatives?...................................................................................................................2-4 Proposed Action..........................................................................................................................................................2-4 Construction Components...........................................................................................................................................2-8 No Build Alternative.....................................................................................................................................................2-9 4 What permits would be required to build the project? .....................................................................................2-9 CHAPTER 3 METHODOLOGY..........................................................................................................................3-1 1 What is the transportation study area?............................................................................................................3-1 2 What horizon years are being considered and why?.......................................................................................3-3 3 What time periods were evaluated and why?..................................................................................................3-3 4 What type of data was collected?....................................................................................................................3-3 5 What other studies and reports were used?....................................................................................................3-3 6 How were traffic volume forecasts developed?...............................................................................................3-5 How was the City of Seattle travel demand model used to predict traffic growth in 2030? .........................................3-5 What land use assumptions were made in the 2030 travel demand model? ..............................................................3-5 What transportation improvements are included in the travel demand model?...........................................................3-6 How were the traffic forecasts developed? .................................................................................................................3-7 How were truck volume forecasts developed?............................................................................................................3-8 7 What methods and criteria were used to evaluate potential effects of the Proposed Action and the No- Build Alternative? ............................................................................................................................................3-8 SR 519 Intermodal Access Project – Phase 2 Transportation Discipline Report Page iii February 2008 Intersection Operations Analysis.................................................................................................................................3-9 Freeway Operations Analysis......................................................................................................................................3-9 Corridor Operations Analysis ....................................................................................................................................3-10 CHAPTER 4 AFFECTED ENVIRONMENT...........................................................................................................4-1 1 What is currently happening with motor vehicle traffic? ..................................................................................4-1 2 What is currently happening with traffic operations?.......................................................................................4-5 How much traffic congestion occurs within the study area?........................................................................................4-5 Where are the bottlenecks in the study area?.............................................................................................................4-8 How long does it take to travel through the study area? .............................................................................................4-9 3 How do events affect traffic conditions through the study area? .....................................................................4-9 Sporting Events.........................................................................................................................................................4-10 Flat Shows ................................................................................................................................................................4-12 4 What is currently happening with railroad crossings at Third Avenue South and at the Tail Tracks?............4-13 What are the railroad facilities in the study area?......................................................................................................4-13 What is the level of train activity in the study area?...................................................................................................4-14 How long are the railroad crossing closures? ...........................................................................................................4-16 How do the crossing closures affect vehicle traffic?..................................................................................................4-17 What are the safety concerns associated with railroad crossings? ...........................................................................4-18 5 What is currently happening with truck traffic?..............................................................................................4-19 Where does commercial traffic go to and from?........................................................................................................4-20 What are the main truck routes? ...............................................................................................................................4-21 What are the existing truck traffic volumes in the study area? ..................................................................................4-23 What is the daily distribution of truck traffic in the study area?..................................................................................4-25 What are the issues associated with current truck operations? 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